NCI sponsors research to improve the delivery of colorectal cancer (CRC) screening in the United States. Colonoscopy is the predominant means by which adults in the U.S. are screened for CRC, but it is not optimally implemented in clinical practice. Poor quality exams and clinical practices that are not evidence-based undermine the procedure?s effectiveness in reducing CRC incidence and mortality. In particular, there is growing evidence that screening and surveillance colonoscopies are being performed at too-frequent intervals, but limited knowledge of why. NCI wishes to further develop the knowledge base for understanding optimal use of colonoscopy for CRC control. NCI therefore will support a project to collect data on colonoscopy practice from an established colonoscopy registry.